Hybrid generator cuts Lime Village energy costs

An experimental hybrid solar-diesel electrical generation system has been operating since late July in Lime Village, a remote community on the Stony River.

It saved the community $2,000 in diesel fuel costs in its first month of operation, according to Phil Graham, a planner for Lime Village Traditional Council and a 25-year resident of the village.

McGrath Power and Light, a private utility in McGrath, the nearest larger community, provides management services.

"While this system is still experimental, it’s an important step in the right direction," Graham said. "We’re making improvements and refinements to make it more reliable, and we’re optimistic about a hybrid solar-diesel system."

Lime Village’s new system is a demonstration project designed to test a hybrid generation plant for remote communities of 50 to 100 people, according to Dennis Meiners, development specialist with the Alaska Energy Authority, a division of the state of Alaska. About 50 people live in Lime Village, an Athabascan community about 100 miles south of McGrath and 200 miles west of Anchorage.

A hybrid system combines power generated from several sources, in this case diesel and solar, Meiners said. The Lime Village project includes 106 solar panels, a direct current to alternating current converter, a small diesel generator and a battery storage bank.

The solar panels used in the project were provided by BP Solar, a subsidiary of BP. Sandia Labs, the research branch of the U.S. Department of Energy, also contributed to the project.

In the Lime Village project, there should be enough light during long summer days to shut off the diesel generator several hours a day, with the village receiving all of its power from the solar panels or solar supplemented by power from storage batteries, Meiners said.

Even during winter, the solar panels will provide some electricity, he said. The key experiment will be determining an optimum combination of diesel and solar power in the hybrid system that reduces diesel costs, Meiners said. There are preliminary indications of savings, but precise data on the experiment will be available after a year, Meiners said.

Fuel costs are very high in Lime Village, as much as $4.50 per gallon, because it must be hauled in small aircraft.

Another objective of the demonstration is to test the efficiency of the new generation of solar panels during low-light conditions in winter. Solar panels will produce electricity from reflection of light off snow as well as direct sunlight, but determining just how much is an objective for BP, said Don Argetsinger, a consultant to BP on the project.

Meiners said very small solar and wind generating sets are now used with batteries to power small remote communications sites in Alaska and elsewhere.

But this is the first experiment Meiners is aware of where a small community will receive its power from a hybrid system and where the efficiency of the experiment will be closely monitored, he said.

Results from the demonstration could be useful in designing small, efficient hybrid systems for other small Alaska rural communities, which could include wind generation as well as solar, Meiners said.

The cost of the new hybrid system was about $160,000, although it was able to use components of an existing generation system at the village.

Meiners said AEA’s original estimates of a conventional diesel-power generation system for the village was about $300,000.

A conventional system would also use more fuel.

Lime Village contributed about $50,000 to the project. BP contributed $45,000 in the value of its solar panels, while the energy authority provided $35,000, most of it in engineering services. Sandia Labs contributed another $30,000.